1. Field of the Invention
The invention relates to a base station of a communication network, preferably a mobile telecommunication network such as an GSM (Global System for Mobile Telecommunication) network, or a packet-switched network such as UMTS (Universal Mobile Telecommunications System), or GPRS (General Packet Radio Service) network.
2. Description of the Prior Art
Telecommunication systems for mobile telecommunication are widely used and require one or more base stations for covering a larger area by high frequency (rf) signals so as to allow serving of e.g. moving subscribers.
The base stations are equipped with an antenna for radiating and receiving rf signals. The antenna increases the outer dimensions of the base station and may also negatively affect the design and visual appearance of the base station. In particular, in case of base stations of a small size such as base stations to be mounted inside a building (e.g. for microcellular structures for indoor applications, or external installations in well visible places), the antenna may hinder the installation at a desired small place.
Furthermore, the physical size of present base stations may be rather small so that it may be difficult to connect the external antennas to the internal components of the base station in an efficient and yet uncomplicated manner. Furthermore, the transmitting and receiving requirements of base stations may be different so that it is difficult to optimize the antenna for these different requirements.
U.S. Pat. No. 5,742,255 discloses an antenna system for a mobile communication which is mounted on the window glass of a vehicle. The antenna system comprises a radiating antenna connected to a conductive plate cooperates with an inner layer, and a microstrip feedline for coupling the rf energy into the interior of the vehicle. The antenna system is quite bulky and necessitates appropriate mounting space.
U.S. Pat. No. 4,724,443 describes a patch antenna having a stripline feed element which is arranged in parallel between two conductive plates of the antenna. One of the plates is a ground plane and connected to the outer shielding of a coaxial cable. The inner conductor of the coaxial cable is connected to the stripline feed element and, at the other side, to an rf source. The antenna is a radiating antenna for transmitting energy to other devices.